TWI660063B - Method for forming protective film for organic EL element, method for manufacturing display device, and display device - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing a display device, which includes a process of forming an organic EL element on a substrate 11 and a process of forming a protective film 16 to cover the organic EL element. The protective film 16 is a laminated film of an insulating film 16a containing Si, an insulating film 16b containing Al, and an insulating film 16c containing Si. The process of forming the protective film 16 includes: a process of forming an insulating film 16a using a plasma CVD method to cover the organic EL element; a process of forming an insulating film 16b on the insulating film 16a by using an ALD method; and A process of forming an insulating film 16c on the insulating film 16b by a slurry CVD method. The present invention can improve the performance of a protective film for an organic EL element.

Description

Method for forming protective film for organic EL element, and method for manufacturing display device And display device

The present invention relates to a method for forming a protective film for an organic EL element, a method for manufacturing a display device, and a display device. For example, the invention is applicable to a method for manufacturing an organic EL display device and an organic EL display device.

As for a light emitting device, development of an organic electroluminescence device using electroluminescence is being carried out. The organic electroluminescence element is called an organic EL element. Electroluminescence is a phenomenon of light emission when a voltage is applied to a substance. In particular, an element that generates organic electroluminescence using an organic substance is referred to as an organic EL element (organic electroluminescence element). The organic EL element is a current injection type device, and because it has the characteristics of a diode, it is also referred to as an Organic Light Emitting Diode (OLED).

Japanese Patent Application Laid-Open No. 2013-187019 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2015-69857 (Patent Document 2) disclose technologies regarding organic EL display devices. Japanese Patent Application Laid-Open No. 2001-284042 (Patent Document 3) discloses a technology related to an organic EL element. Japanese Patent Application Laid-Open No. 2006-278486 (Patent Document 4) discloses a technique for forming a film using an atomic layer deposition (ALD) method. International Publication No. 2012/039310 (Patent Document 5) discloses a technique related to a method of manufacturing an organic EL element.

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2013-187019

[Patent Document 2] Japanese Patent Laid-Open No. 2015-69857

[Patent Document 3] Japanese Patent Laid-Open No. 2001-284042

[Patent Document 4] Japanese Patent Laid-Open No. 2006-278486

[Patent Document 5] International Publication No. 2012/039310

Since the organic EL element is afraid of water, it is desirable to form a protective film to cover the organic EL element and prevent moisture from being transmitted to the organic EL element. It is also desired to improve the performance of a protective film for an organic EL element.

Other problems and novel features are clearly presented in the description and drawings of this specification.

In one embodiment, the method for forming a protective film includes the following steps: (a) forming a first insulating film containing Si using a plasma CVD method to cover the organic EL element; (b) forming a first insulating film A second insulating film containing Al is formed using the ALD method; (c) a third insulating film containing Si is formed on the second insulating film using the plasma CVD method; wherein, the first insulating film, the first insulating film, A laminated film composed of two insulating films and the third insulating film to form the protective film for an organic EL element.

According to one embodiment, the performance of the protective film for an organic EL element can be improved.

1‧‧‧ display device

2‧‧‧Display

3‧‧‧Circuit Department

4‧‧‧ area

9‧‧‧ glass substrate

10‧‧‧ substrate

11‧‧‧ substrate

12‧‧‧ passivation film

13, 13a‧‧‧ electrode layer

14‧‧‧ organic layer

15, 15a‧‧‧electrode layer

16‧‧‧ protective film

16a, 16b, 16c‧‧‧ insulating film

17‧‧‧ resin film

21‧‧‧Film forming device

22‧‧‧Load Lock Room

23‧‧‧ transfer room

24 ~ 26‧‧‧ chamber

27‧‧‧ Object to be processed

31‧‧‧Workbench

32‧‧‧ sprinkler

33‧‧‧ Antenna

34‧‧‧Exhaust

41‧‧‧Workbench

42‧‧‧upper electrode

43‧‧‧Exhaust

44‧‧‧Gas introduction department

45‧‧‧Gas discharge section

PH‧‧‧ pinhole

T1 ~ T3‧‧‧thickness

S1 ~ S7‧‧‧step

S6a ~ S6c‧‧‧step

[FIG. 1] FIG. 1 is a plan view showing the overall configuration of a display device in an embodiment.

[Fig. 2] Fig. 2 is a plan view of a main part of a display device in an embodiment.

[Fig. 3] Fig. 3 is a sectional view of a main part of a display device in an embodiment.

[FIG. 4] FIG. 4 is a flowchart showing a manufacturing process of a display device in an embodiment.

[FIG. 5] FIG. 5 is a flowchart showing a protective film forming process in the manufacturing process of the display device in one embodiment.

[Fig. 6] Fig. 6 is a cross-sectional view of a main part in a manufacturing process of a display device in an embodiment.

[Fig. 7] Fig. 7 is a sectional view of a main part in the manufacturing process of the display device continued from Fig. 6. [Fig.

[FIG. 8] FIG. 8 is a cross-sectional view of a main part in the manufacturing process of the display device continued from FIG. 7. [FIG.

[Fig. 9] Fig. 9 is a sectional view of a main part in the manufacturing process of the display device continued from Fig. 8. [Fig.

[Fig. 10] Fig. 10 is a sectional view of a main part in the manufacturing process of the display device continued from Fig. 9. [Fig.

[FIG. 11] FIG. 11 is a sectional view of a main part in the manufacturing process of the display device continued from FIG. 10.

[Fig. 12] Fig. 12 is a sectional view of a main part in the manufacturing process of the display device continued from Fig. 11. [Fig.

[FIG. 13] FIG. 13 is a cross-sectional view of a main part in the manufacturing process of the display device continued from FIG.

14 is an explanatory diagram showing an example of a film forming apparatus for forming a protective film.

[FIG. 15] FIG. 15 is a cross-sectional view showing an example of the configuration of a film-forming chamber using a plasma CVD method.

[FIG. 16] FIG. 16 is a cross-sectional view showing an example of a configuration of a film-forming chamber using an ALD method.

[Fig. 17] Fig. 17 is a partially enlarged sectional view showing a part of Fig. 9 in an enlarged manner.

[FIG. 18] FIG. 18 is a partially enlarged sectional view showing a part of FIG. 10 in an enlarged manner.

[Fig. 19] Fig. 19 is a partially enlarged sectional view showing a part of Fig. 11 in an enlarged manner.

20 is a cross-sectional view of a comparative example.

[FIG. 21] FIG. 21 is a cross-sectional view schematically showing that a flexible substrate is bent when the flexible substrate is used as a display device substrate.

[Fig. 22] Fig. 22 is a graph showing the experimental results obtained with respect to the moisture transmittance of the protective film.

In the following embodiments, although they are divided into a plurality of sections or embodiments for the sake of convenience of explanation, these sections or embodiments are not unrelated except for the case where it is specifically stated. Some or all of them have a relationship with changes, detailed introductions, and supplementary explanations. At the same time, in the following embodiments, when referring to the required number (including the number, value, quantity, range, etc.), it is not limited to it except that it is specifically stated and in principle that it must be limited to a specific number. The specific number may be above or below the specific number. Next, in the following embodiments, the constituent elements (including necessary steps, etc.) are not required to be necessary unless the constituent elements are explicitly and theoretically necessary. Similarly, in the following embodiments, when the shape and positional relationship of the constituent elements and the like are discussed, in addition to the case where the shape and the positional relationship of the non-constituent elements and the like are clearly specified in principle, it also includes the substance. Similar or similar to those shapes. The same applies to the above numerical values and ranges.

Hereinafter, embodiments will be described in detail based on the drawings. In addition, in all the drawings for explaining the embodiment, components having the same function are given the same reference numerals, and repeated descriptions are omitted. At the same time, in the following embodiments, the description of the same or the same part is omitted in principle unless otherwise necessary.

At the same time, with regard to the drawings used in the embodiment, in order to make the drawings easier to understand, even cross-sections may be omitted. At the same time, in order to make the drawings easier to understand, even plan views may be given hatching.

(Form of implementation)

<For the overall structure of the display device>

The display device of this embodiment is an organic EL display device (organic electroluminescence display device) using an organic EL element. The display device of this embodiment will be described with reference to the drawings.

FIG. 1 is a plan view showing the overall configuration of a display device 1 in this embodiment.

As shown in FIG. 1, the display device 1 includes a display section 2 and a circuit section 3. A plurality of pixels are arranged in an array in the display unit 2 and an image can be displayed. In the circuit section 3, various circuits can be formed as necessary, for example, a drive circuit, a control circuit, and the like. The circuits in the circuit section 3 may be connected to the pixels of the display section 2 as necessary. The circuit section 3 may be provided outside the display device 1. Although the planar shape of the display device 1 can adopt various shapes, it is preferably rectangular, for example.

FIG. 2 is a plan view of a main part of the display device 1, and FIG. 3 is a cross-sectional view of a main part of the display device 1. In FIG. 2, a part of the display section 2 (area 4 in FIG. 1) of the display device 1 is enlarged and displayed. FIG. 3 is a cross-sectional view almost corresponding to the position of the line A1-A1 in FIG. 2.

The substrate 11 constituting the base of the display device 1 is insulating. At the same time, the substrate 11 is a flexible substrate (thin film substrate), so it has flexibility. Therefore, the substrate 11 is a flexible substrate having insulation properties, that is, a flexible insulating substrate. The substrate 11 may further have translucency. As the substrate 11, for example, a film-like plastic substrate (plastic film) can be used. The substrate 11 exists on the entire plane of the display device 1 in FIG. 1 and constitutes the lowermost layer of the display device 1. Therefore, the planar shape of the substrate 11 is almost the same as the planar shape of the display device 1. Although various shapes can be adopted, it is preferably rectangular, for example. Moreover, in Among the two main surfaces located on the opposite sides of the substrate 11, the main surface on which the organic EL element is disposed, that is, a passivation film 12, an electrode layer 13, an organic layer 14, an electrode layer 15, and a protective film described later will be formed The main surface on the side of 16 is referred to as the top surface of the substrate 11. Meanwhile, the main surface on the side opposite to the top surface of the substrate 11 is referred to as the bottom surface of the substrate 11.

On the top surface of the substrate 11, a passivation film (passivation layer) 12 is formed. The passivation film 12 is made of an insulating material (insulating film), for example, a silicon oxide film. Although the passivation film 12 may not be formed, the passivation film 12 is preferably formed. The passivation film 12 can be formed on the top surface that is almost equivalent to the entire substrate 11.

The passivation film 12 has a function of preventing (blocking) moisture from the substrate 11 from being conducted to the organic EL element (in particular, the organic layer 14). Therefore, the passivation film 12 has a function as a protective film under the organic EL element. On the other hand, the protective film 16 has a function as a protective film on the upper side of the organic EL element and preventing (blocking) moisture from the upper side from being conducted to the organic EL element (especially the organic layer 14).

On the top surface of the substrate 11, an organic EL element is formed through the passivation film 12. The organic EL element includes an electrode layer 13, an organic layer 14, and an electrode layer 15. That is, on the passivation film 12 of the substrate 11, the electrode layer 13, the organic layer 14, and the electrode layer 15 are formed (laminated) from bottom to top, and the electrode layer 13, the organic layer 14, and the electrode layer 15 An organic EL element is formed.

The electrode layer 13 is a lower electrode layer, and the electrode layer 15 is an upper electrode layer. The electrode layer 13 constitutes one of the anode or the cathode, and the electrode layer 15 constitutes the other of the anode or the cathode. That is, in the case of the electrode layer 13 being the anode (anode layer), the electrode layer 15 is the cathode (cathode layer), and in the case of the electrode layer 13 being the cathode (cathode layer), the electrode layer 15 is the anode (anode layer) ). The electrode layer 13 and the electrode layer 15 are each formed of a conductive film.

In order to have the function of a reflective electrode, one of the electrode layer 13 and the electrode layer 15 is preferably formed of a metal film such as an aluminum (Al) film, and to have the function of a transparent electrode, the electrode layer 13 and the electrode layer The other of 15 is preferably formed of a transparent conductor film such as ITO (indium tin oxide). When the light is emitted from the bottom surface of the substrate 11, that is, when the bottom emission method is used, the electrode layer 13 can be used as a transparent electrode, and the light is emitted from the top surface of the substrate 11, that is, when the top emission method is used, the electrode layer 15 can be used. As a transparent electrode. Meanwhile, in the case of adopting the bottom emission method, a transparent substrate (transparent flexible substrate) having translucency can be used as the substrate 11.

Since the electrode layer 13 is formed on the passivation film 12 on the substrate 11, the organic layer 14 is formed on the electrode layer 13, and the electrode layer 15 is formed on the organic layer 14, there is an organic layer between the electrode layer 13 and the electrode layer 15. 14.

The organic layer 14 includes at least an organic light emitting layer. In addition to the organic light emitting layer, the organic layer 14 may include any one of a hole transport layer, a hole injection layer, an electron transport layer, and an electron injection layer as necessary. Therefore, for example, the organic layer 14 may have a structure of a single organic light emitting layer, a hole transporting layer, a laminated structure of an organic light emitting layer and an electron transporting layer, or a hole injection layer, a hole transporting layer, or organic light emitting. Layer, electron transport layer and electron injection layer.

For example, the electrode layer 13 has a stripe-shaped form extending in the X direction. In other words, the electrode layer 13 has a configuration in which stripe-shaped electrodes (electrode forms) 13 a extending in the X direction and arranged in plural in a predetermined interval in the Y direction. For example, the electrode layer 15 has a stripe-shaped form extending in the Y direction. In other words, the electrode layer 15 has a configuration in which stripe-shaped electrodes (electrode forms) 15 a extending in the Y direction and arranged in plural in a predetermined interval in the X direction. That is, the electrode layer 13 is composed of a stripe electrode group extending in the X direction, and the electrode layer 15 is composed of a stripe electrode group extending in the Y direction. to make. Here, the directions where the X direction and the Y direction intersect, and more specifically, are directions orthogonal to each other. At the same time, the X direction and the Y direction may be directions parallel to the top surface of the substrate 11.

Since the extension direction of each electrode 15a constituting the electrode layer 15 is the Y direction, and the extension direction of each electrode 13a constituting the electrode layer 13 is the X direction, the electrode layer 15 and the electrode layer 13 intersect in a plan view. In addition, the top view refers to a case of being viewed in a plane slightly parallel to the top surface of the substrate 11. Each of the intersecting portions between the electrode 15a and the electrode 13a has a structure in which the organic layer 14 is sandwiched between the upper and lower portions of the electrode 15a and the electrode 13a. Therefore, an organic EL element (an organic EL element constituting a pixel) is formed at each intersecting portion between the electrode 15a and the electrode 13a. The organic EL element includes an electrode 13a, an electrode 15a, and an organic layer 14 between the electrode 13a and the electrode 15a. And a pixel is formed by the organic EL element. By applying a specific voltage between the electrode 15a and the electrode 13a, the organic light emitting layer sandwiched between the electrode 13a and a part of the organic layer 14 between the electrodes 15a can emit light. That is, the organic EL elements constituting each pixel can be made to emit light. The electrode 15a functions as the upper electrode (one of the anode or the cathode) of the organic EL element, and the electrode 13a functions as the lower electrode (the other of the anode or the cathode) of the organic EL element.

Furthermore, although the organic layer 14 may be formed on the entire display portion 2, it may be formed in the same form as the electrode layer 13 (that is, the same form as the plurality of electrodes 13 a constituting the electrode layer 13) or may be formed in the same manner as the electrode layer 15. The same form (that is, the same form as the plurality of electrodes 15 a constituting the electrode layer 15). In any case, the organic layer 14 exists at each intersection between the plurality of electrodes 13 a constituting the electrode layer 13 and the plurality of electrodes 15 a constituting the electrode layer 15.

In this way, in the display section 2 of the display device 1 in a plan view, the organic EL elements (pixels) are formed in a state of being arrayed in a plurality of arrays on the substrate 11.

Furthermore, the case where the electrode layers 13 and 15 have a stripe form has been described here. Therefore, for a plurality of organic EL elements (pixels) arranged in an array, In the organic EL in the vertical direction, the lower electrodes (electrodes 13a) are connected to each other, and in the organic EL parallel to the Y direction, the upper electrodes (electrodes 15a) are connected to each other. However, the structure of the organic EL elements arranged in an array can be variously changed and is not limited thereto.

For example, the upper electrode and the lower electrode of a plurality of organic EL elements arranged in an array may not be connected to each other, but may be arranged independently. In this case, each organic EL element is formed in an isolated form having a lower electrode, an organic layer, and an upper electrode structure, and the isolated plural organic EL elements are arranged in an array. In this case, an active element such as a TFT (Thin Film Transistor) is added to the organic EL element of each pixel, and each pixel can be connected through wiring as necessary.

In order to coat the organic EL element and to coat the electrode layer 13, the organic layer 14, and the electrode layer 15, a protective film (protective layer) 16 is formed on the top surface of the substrate 11 (passivation film 12). In order to cover these organic EL elements arranged in an array, a protective film 16 is formed when the array of organic EL elements is arranged in the display section 2. Therefore, the protective film 16 is preferably formed on the entire display 2 and is preferably formed on the entire top surface of the substrate 11. By using the protective film 16 to cover the organic EL element (the electrode layer 13, the organic layer 14, and the electrode layer 15), the organic EL element (the electrode layer 13, the organic layer 14, and the electrode layer 15) can be protected. The protective film 16 prevents (blocks) moisture from being conducted to the organic EL element, and particularly prevents (blocks) moisture from being conducted to the organic layer 14. That is, by providing the protective film 16, it is possible to prevent moisture from entering the organic EL element beyond the protective film 16. The protective film 16 is a protective film for an organic EL element.

However, there are cases where it is necessary to expose a part of an electrode, a wiring, or the like from the protective film 16. In this case, the protective film 16 is not formed on the entire area of the top surface of the substrate 11, but a region where the protective film 16 is not formed is provided on a part of the top surface of the substrate 11. (A region where the protective film 16 is not formed) is exposed. However, even in such a case, the organic layer 14 is preferably not exposed from a region where the protective film 16 is not formed.

In this embodiment, the protective film 16 is a laminated film of an insulating film (insulating layer) 16a, an insulating film (insulating layer) 16b on the insulating film 16a, and an insulating film (insulating layer) 16c on the insulating film 16b. . In other words, the protective film 16 includes three layers such as an insulating film 16a, an insulating film 16b, and an insulating film 16c.

Among the insulating film 16a, the insulating film 16b, and the insulating film 16c constituting the protective film 16, the insulating film 16a and the insulating film 16c are each an insulating film formed by a plasma CVD (Chemical Vapor Deposition) method. The insulating film 16b is an insulating film formed by an ALD (Atomic Layer Deposition) method. The insulating film 16a and the insulating film 16c are each preferably formed by an ICP (Inductively Coupled Plasma) -CVD method (Chemical Vapor Deposition).

As for the insulating film 16a, although a silicon nitride film, a silicon oxide film, or a silicon oxynitride film can be selected, a silicon nitride film is most preferable. Meanwhile, as for the insulating film 16c, although a silicon nitride film, a silicon oxide film, or a silicon oxynitride film can be selected, a silicon nitride film is most preferable.

As for the insulating film 16b, although an insulating film containing aluminum (Al), such as an aluminum oxide film, an aluminum oxynitride film, or an aluminum nitride film, can be selected, among these, an aluminum oxide film or an aluminum oxynitride film is particularly preferred. .

A resin film (resin layer, resin insulating film, organic insulating film) 17 is formed on the protective film 16. That is, a resin film 17 is formed on the insulating film 16c. As a material of the resin film 17, for example, PET (polyethylene terephthalate) can be applied.

The formation of the resin film 17 may be omitted. However, it is preferable to form the resin film 17 rather than the case where the resin film 17 is not formed. Since the resin film 17 is soft, the display device 1 can be easily handled by providing the resin film 17.

<Manufacturing Method of Display Device>

A method of manufacturing the display device 1 according to this embodiment will be described with reference to the drawings. FIG. 4 is a flowchart showing a manufacturing process of the display device 1 in this embodiment. FIG. 5 is a flowchart showing details of a process of forming the protective film 16 in the manufacturing process of the display device 1 in this embodiment. 6 to 13 are cross-sectional views of main parts during the manufacturing process of the display device 1 in this embodiment, and correspond to the cross-sectional views of the area shown in FIG. 3 described above. The manufacturing process of the display unit 2 of the display device 1 will be mainly described here.

As shown in FIG. 6, a substrate 10 on which a glass substrate 9 and a substrate 11 as a flexible substrate are bonded is prepared (prepared) (step S1 in FIG. 4). Although the substrate 11 has flexibility, the substrate 11 is fixed to the glass substrate 9 by bonding the substrate 11 to the glass substrate 9. Thereby, the formation of various films or the processing of such films on the substrate 11 is facilitated. The bottom surface of the substrate 11 is attached to a glass substrate 9.

Next, as shown in FIG. 7, a passivation film 12 is formed on the top surface of the substrate 10 (step S2 in FIG. 4). The top surface of the substrate 10 is synonymous with the top surface of the substrate 11.

The passivation film 12 can be formed using a sputtering method, a CVD method, an ALD method, or the like. The passivation film 12 is made of an insulating material, for example, a silicon oxide film. For example, a silicon oxide film formed by a CVD method is suitably used as the passivation film 12.

Next, as shown in FIG. 8, an electrode layer 13, an organic layer 14 on the electrode layer 13, and an electrode layer 15 on the organic layer 14 are formed on the top surface of the substrate 10, that is, on the passivation film 12. Organic EL element. That is, the electrode layer 13, the organic layer 14, and the electrode layer 15 are sequentially formed on the passivation film 12 (steps S3, S4, and S5 in FIG. 4). For example, the process can be performed as follows.

That is, an electrode layer 13 is formed on the top surface of the substrate 10, that is, on the passivation film 12 (step S3 in FIG. 4). For example, the electrode layer 13 can be formed by forming a conductive film on the passivation film 12 and then patterning it using photolithography and etching techniques. Thereafter, an organic layer 14 is formed on the electrode layer 13 (step S4 in FIG. 4). For example, the organic layer 14 can be formed by a vapor deposition method (vacuum vapor deposition method) using a mask. After that, an electrode layer 15 is formed on the organic layer 14 (step S5 in FIG. 4). For example, the electrode layer 15 can be formed by a vapor deposition method using a mask.

After the organic EL element including the electrode layer 13, the organic layer 14, and the electrode layer 15 is formed, a protective film 16 is formed on the top surface of the substrate 10, that is, on the electrode layer 15 (step S6 in FIG. 4). The protective film 16 is formed so as to cover the organic EL element.

Since the protective film 16 is a laminated film of the insulating film 16a, the insulating film 16b on the insulating film 16a, and the insulating film 16c on the insulating film 16b, as shown in FIG. 5, the protective film 16 in step S6 The formation process includes an insulation film 16a formation process of step S6a, an insulation film 16b formation process of step S6b, and an insulation film 16c formation process of step S6c. After the insulating film 16a forming process of step S6a is performed, the insulating film 16b forming process of step S6b is performed, and then the insulating film 16c forming process of step S6c is performed.

Therefore, specifically, the process of forming the protective film 16 in step S6 can be performed as follows. That is, first, as shown in FIG. 9, an insulating film 16a is formed on the substrate 10, that is, on the electrode layer 15, by a plasma CVD method (step S6a in FIG. 5). The insulating film 16a is formed so as to cover the organic EL element. Thereafter, as shown in FIG. 10, an insulating film 16b is formed on the insulating film 16a by the ALD method (step S6b in FIG. 5). Thereafter, as shown in FIG. 11, an insulating film 16c is formed on the insulating film 16b by a plasma CVD method (step S6c in FIG. 5). Thereby, the protective film 16 formed by laminating the insulating film 16a, the insulating film 16b on the insulating film 16a, and the insulating film 16c on the insulating film 16b is formed.

At the same time, there is a case where a part of an electrode, a wiring, or the like must be exposed from the protective film 16. In this case, the protective film 16 is not formed on the entire area of the top surface of the substrate 10, but a region where the protective film 16 is not formed is provided on a part of the top surface of the substrate 10, and a part of the electrode, wiring, etc. can be removed from this portion (A region where the protective film 16 is not formed) is exposed. For example, in this case, the process of forming the protective film 16 in step S6 can be performed as follows. That is, first, a mask (metal mask) is disposed on the substrate 10, that is, on the electrode layer 15, and then an insulating film 16a is formed using a plasma CVD method. After that, the mask is removed, and the next mask (metal mask) is arranged on the substrate 10, that is, on the electrode layer 15, and then the insulating film 16b is formed on the insulating film 16a by using the ALD method. After that, the mask is removed, and the next mask (metal mask) is arranged on the substrate 10, that is, on the electrode layer 15, and then an insulating film 16c is formed on the insulating film 16b by a plasma CVD method. This mask is then removed. Thereby, the protective film 16 formed by laminating the insulating film 16a, the insulating film 16b, and the insulating film 16c is formed. Although the insulating film 16a, the insulating film 16b, and the insulating film 16c are formed in the exposed area not covered by the mask, and the protective film 16 is formed, the insulating film 16a, the insulating film 16b, and The protective film 16 is not formed on the insulating film 16c. Thereby, while forming the protective film 16 so that the organic EL element can be covered, if necessary, electrodes, wirings, and the like can be exposed from a region where the protective film 16 is not formed.

In any case, in steps S6a and S6c, the insulating film 16a and the insulating film 16c are formed using a plasma CVD method, and in step S6b, the insulating film 16b is formed using an ALD method. In steps S6a and S6c, an ICP-CVD method is preferably used.

Although detailed below, in order to fill the pinholes formed in the insulating film 16a with the insulating film 16b, the pinholes are generated when the insulating film 16a is formed using the plasma CVD method, and thus the insulating film 16b is formed. . Therefore, in step S6b, the insulating film 16b is formed on the insulating film 16a using the ALD method. The insulating film 16b is brought into contact with the insulating film 16a. Meanwhile, although detailed later, in order to prevent the insulating film 16b from contacting and reacting with moisture, the insulating film 16c is formed. Therefore, in step S6c, an insulating film 16c is formed on the insulating film 16b using a plasma CVD method, and the insulating film 16c is brought into contact with the insulating film 16b. Therefore, if steps S6a, S6b, and S6c are completed, a protective film 16 formed by laminating the insulating film 16a, the insulating film 16b, and the insulating film 16c is formed, and the insulating film 16b is formed on the insulating film 16a and the insulating film 16a At the same time, the insulating film 16c is formed on the insulating film 16b and is in contact with the insulating film 16b. Furthermore, in step S6a, an insulating film 16c is formed to cover the organic EL element, and a protective film 16 is formed to cover the organic EL element.

Because the organic EL element (especially the organic layer 14) is not resistant to high temperatures, in order not to adversely affect the organic EL element (especially the organic layer 14), the film forming temperatures of the steps S6a, S6b, and S6c, that is, the insulating films 16a, The respective film formation temperatures of the insulating film 16b and the insulating film 16c are preferably relatively low temperatures, specifically, preferably 100 ° C or lower, and may be, for example, about 80 ° C.

In order to form a dense film at such a low film forming temperature, as for the insulating films 16a and 16c using a plasma CVD method, it is preferable to use a silicon nitride film, a silicon oxide film, or a silicon oxynitride film. Among others, a silicon nitride film is particularly preferred. Meanwhile, for the insulating film 16b using the ALD method, it is preferable to use an aluminum oxide film, an aluminum nitride oxide film, or an aluminum nitride film, but among these, an aluminum oxide film or an aluminum nitride oxide film is particularly preferred.

When the protective film 16 is formed, the organic EL element including the electrode layer 13, the organic layer 14, and the electrode layer 15 is covered with the protective film 16. When a plurality of organic EL elements are arranged in an array, the protective film 16 covers the plurality of organic EL elements.

After the protective film 16 is formed in step S6, as shown in FIG. 12, a resin film 17 is formed on the top surface of the substrate 10, that is, on the protective film 16 (step S7 in FIG. 4).

Since the uppermost layer of the protective film 16 is an insulating film 16c, a resin film 17 is formed on the insulating film 16c. For example, the resin film 17 may be made of PET or the like and used a spin coating method (coating method).

Thereafter, as shown in FIG. 13, the substrate 11 is separated from the glass substrate 9 by pulling the substrate 11 away from the glass substrate 9 and the structures on the top surface thereof. In this way, the display device 1 can be manufactured.

FIG. 14 is an explanatory diagram showing an example of a film forming apparatus for forming the protective film 16.

The film forming apparatus 21 of FIG. 14 is a multi-chamber type film forming apparatus having a plurality of chambers. Specifically, the film forming apparatus 21 includes a load lock chamber 22, a transfer chamber 23, and a plurality of chambers (processing chamber, film forming chamber) 24, 25, and 26. Among them, the chambers 24 and 26 are chambers for forming a film using a plasma CVD method, and the chambers 25 are chambers for forming a film using an ALD method. The cavity 24 is used to form the insulating film 16a, the cavity 25 is used to form the insulation film 16b, and the cavity 26 is used to form the insulation film 16c. Hereinafter, a process flow chart of forming the protective film 16 using the film forming apparatus 21 will be described.

First, after the process before the protective film 16 formation process is completed, in order to perform the protective film 16 formation process, the object to be processed is carried into the load lock chamber 22 of the film forming apparatus 21. Here, the object to be processed carried into the load lock chamber 22 is a substrate 10 on which the above-mentioned passivation film 12, electrode layer 13, organic layer 14, and electrode layer 15 are formed, and the structure of FIG. 8 is formed on the substrate 10, In FIGS. 15 and 16 to be described later, reference numeral 27 is given and indicated as an object 27 to be processed.

Then, the object to be processed carried into the load lock chamber 22 is transferred (vacuum transferred) into the chamber 24 via the transfer chamber 23. Next, an insulating film 16a was formed on the object to be processed disposed in the chamber 24 using a plasma CVD method. At this time, the above-mentioned step S6a is performed in the chamber 24. After that, the object to be processed in the chamber 24 is transferred (vacuum transferred) into the chamber 25 via the transfer chamber 23. Next, an ALD method is used for the object to be processed disposed in the chamber 25. An insulating film 16b is formed. At this time, the above-mentioned step S6b is performed in the chamber 25. Then, the object to be processed in the chamber 25 is transferred (vacuum transferred) into the chamber 26 via the transfer chamber 23. Next, an insulating film 16c was formed on the object to be processed disposed in the chamber 26 by a plasma CVD method. At this time, the above-mentioned step S6c is performed in the chamber 26. Then, the object to be processed in the chamber 26 is transferred (vacuum transferred) to the load lock chamber 22 via the transfer chamber 23. After that, the object to be processed is carried out from the load lock chamber 22 to the outside of the film forming apparatus 21, and is transferred to a manufacturing apparatus that performs the next process (for example, the resin film 17 forming process).

Meanwhile, in the film forming apparatus 21, two load lock chambers for a load lock chamber for carrying in and a load lock chamber for carrying out can be provided. At this time, the to-be-processed object is carried into the load lock chamber for carrying in, and is transported via the transfer chamber 23, and the processes of steps S6a, S6b, and S6c are performed in the chambers 24, 25, and 26. The load lock chamber for carrying out is carried out to the outside of the film forming apparatus 21 and is carried to the next process.

At the same time, in each of the film-forming processes of the insulating films 16a, 16b, and 16c, when a film is formed with a mask placed on the object to be processed, the mask chamber (mask chamber) for removing the mask and The transfer chamber 23 is connected, and the mask can be removed in the mask chamber.

If the film forming apparatus 21 of FIG. 14 is used, the above-mentioned step S6a (the insulating film 16a forming process), the above-mentioned step S6b (the insulating film 16b forming process), and the above-mentioned step S6c (the insulating film 16c forming process) do not expose the object to be processed It can be carried out continuously in the atmosphere. Thereby, after the insulating film 16a is formed in step S6a, an unnecessary film is not formed on the surface of the insulating film 16a, and the insulating film 16b can be formed on the insulating film 16a in step S6b. At the same time, after the insulating film 16b is formed in step S6b An unnecessary film is not formed on the surface of the insulating film 16b, and the insulating film 16c can be formed on the insulating film 16b in step S6c. Thereby, the protective film 16 formed of the laminated film of the insulating film 16a, the insulating film 16b, and the insulating film 16c can be more reliably formed, and the effect of preventing the invasion of moisture generated by the protective film 16 can be obtained more reliably. .

FIG. 15 is a cross-sectional view showing an example of the configuration of a chamber 24 formed by a plasma CVD method. Since the configuration of the chamber 26 is also the same as that of the chamber 24 in FIG. 15, the chamber 24 is represented here as 26 and the configuration of the chamber 24 will be described with reference to FIG. 15.

As shown in FIG. 15, a table 31 for arranging the object 27 to be processed, a shower head (gas supply section) 32 disposed above the table 31, and a shower head 32 are disposed in the chamber 24. Of the antenna 33. The antenna 33 is located between the table 31 and the shower head 32, and is disposed close to the shower head 32. Furthermore, in FIG. 15, within the cavity 24, the antenna 33 extends in a direction slightly perpendicular to the paper surface. The exhaust portion (exhaust port) 34 of the chamber 24 is connected to a vacuum pump (not shown), and can control the inside of the chamber 24 to a specific pressure.

When the film is formed using the chamber 24, the film-forming gas is released from the shower head 32 into the chamber 24, and high-frequency power is applied near the antenna 33. In the case of forming a silicon nitride film, the film-forming gas is, for example, a mixed gas of a SiH ₄ gas (silane gas) and an NH ₃ gas (ammonia gas). The gas is plasmatized to generate a chemical reaction, and the obtained SiN (silicon nitride) particles are deposited on an object 27 to be processed disposed on the table 31 to form a silicon nitride film.

FIG. 16 is a cross-sectional view showing an example of the configuration of a chamber 25 formed by the ALD method.

As shown in FIG. 16, a table 41 for arranging the object to be processed 27 and an upper electrode 42 disposed above the table 41 are arranged in the chamber 25. The exhaust portion (exhaust port) 43 of the chamber 25 is connected to a vacuum pump (not shown), and the inside of the chamber 25 can be controlled to a specific pressure. At the same time, a gas introduction portion 44 for introducing gas into the chamber 25 and a gas discharge portion 45 for discharging gas from the inside of the chamber 25 are arranged in the chamber 25. Note that in FIG. 16, for ease of understanding, the flow direction of the gas introduced from the gas introduction portion 44 into the chamber 25 and the flow direction of the gas discharged from the gas discharge portion 44 to the outside of the chamber 25 are briefly shown as arrows. .

For example, the film formation system using the chamber 25 can be performed as follows.

First, as a first step, a source gas is introduced into the chamber 25 from the gas introduction portion 44. In the case of forming an alumina film, as the raw material gas, for example, TMA (Trimethylaluminium) gas can be used. Raw material gas molecules are adsorbed on the surface of the object 27 to be processed disposed on the table 41.

Next, as a second step, the introduction of the source gas into the chamber 25 is stopped, and the purge gas is introduced into the chamber 25 from the gas introduction portion 44. As the purge gas, for example, an inert gas can be used, for example. By introducing the purge gas, although the adsorbed source gas molecules still remain on the surface of the object 27 to be processed, the other source gases are purged from the gas exhaust portion 45 to the outside of the chamber 25 together with the purge gas. (Purged).

Next, as a third step, a reaction gas is introduced into the chamber 25 from the gas introduction portion 44. In the case of forming an aluminum oxide film, as the reaction gas, for example, O ₂ (oxygen) gas can be used, for example. Next, high-frequency power is applied between the upper electrode 42 and the table 41. Thereby, an alumina atomic layer (one layer) is formed on the surface of the object 27 to be processed.

Next, as a fourth step, the introduction of the reaction gas into the chamber 25 and the application of high-frequency power to the upper electrode 42 are stopped, and the purge gas is introduced into the chamber 25 from the gas introduction portion 44. As the purge gas, for example, an inert gas can be used, for example. By introducing an inert gas, the reaction gas is discharged from the gas discharge portion 45 to the outside of the chamber 25 (purged) together with the purge gas.

By repeating such a first step, a second step, a third step, and a fourth step several times, a desired film (for example, an aluminum oxide film) having a desired thickness can be formed on the surface of the object 27 to be processed.

In the case where the insulating film 16a is a silicon nitride film formed in the chamber 24, the film formation conditions of the silicon nitride film include, for example, the following conditions. In other words, the substrate temperature (film formation temperature) is 80 ° C, the flow rate of SiH ₄ gas is 100 sccm, the flow rate of NH ₃ gas is 150 sccm, radio frequency (RF, radio frequency) energy (high-frequency energy) is 1000 W, and film formation speed is 100nm / min.

In the case where the insulating film 16b is an alumina film formed in the chamber 25, the film formation conditions of the alumina film are, for example, the following conditions. In other words, the substrate temperature (film formation temperature) is 80 ° C, the flow rate of TMA gas is 50 sccm, the flow rate of O ₂ gas is 400 sccm, radio frequency (RF, radio frequency) energy (high frequency energy) is 800 W, and the film formation speed is 4 nm. /Minute.

In the case where the insulating film 16c is a silicon nitride film formed in the chamber 26, the film formation conditions of the silicon nitride film include, for example, the following conditions. In other words, the substrate temperature (film formation temperature) is 80 ° C, the flow rate of SiH ₄ gas is 100 sccm, the flow rate of NH ₃ gas is 150 sccm, radio frequency (RF, radio frequency) energy (high-frequency energy) is 1000 W, and film formation speed is 100nm / min.

<About the process of discussion>

Since the organic EL element is not resistant to water, in order to cover the organic EL element, it is desirable to form a protective film (a moisture protection film) to prevent moisture transmitted to the organic EL element. This protective film is suitable for an inorganic insulating film containing Si formed by a plasma CVD method. Since an inorganic insulating film containing Si formed by a plasma CVD method can be formed at a low temperature and has a high film density, it is suitable as a protective film for preventing the transmission of moisture. Furthermore, since the organic EL element is not resistant to high temperatures and deteriorates when exposed to high temperatures, it is desirable that the film formation temperature of the protective film be lowered to some extent. Here, the inorganic insulating film containing Si is an inorganic insulating film using Si (silicon) as a constituent element, and may be, for example, a silicon nitride film, a silicon oxide film, or a silicon oxynitride film.

However, a film formed using a plasma CVD method has a concern that defects such as pinholes (small holes) are formed during film formation. If a protective film having a pinhole formed thereon is used as it is, moisture may penetrate into the pinhole and be transmitted to the organic EL element, and the organic EL element may be deteriorated.

Therefore, after forming an inorganic insulating film containing Si by using a plasma CVD method, it is considered to form ALD on the inorganic insulating film containing Si for the purpose of filling the pinholes formed during film formation. membrane. Here, a film formed using the ALD method is referred to as an ALD film. Since the ALD method is a film formation method for step height or holes with high covering properties, even when an inorganic insulating film containing Si is formed using a plasma CVD method, pinholes are formed in the inorganic insulating film containing Si as long as it is formed. The ALD film on the inorganic insulating film containing Si can fill the pinholes of the inorganic insulating film containing Si by the ALD film. This can prevent moisture from being transmitted to the organic EL element through the pinhole. In the ALD film for filling pinholes, it is desirable to use an insulating film containing Al in a manner capable of forming a dense film at a low temperature. Here, the insulating film containing Al is an insulating film using aluminum (Al) as a constituent element, and may be, for example, an aluminum oxide film, an aluminum nitride oxide film, or an aluminum nitride film.

If an ALD method is used to form a silicon oxide film or a silicon nitride film, the film formation temperature must be high to a certain degree. If an ALD method is used to form a silicon oxide film or a silicon nitride film at a temperature as low as a certain degree in order to consider the influence on the organic EL element, it is difficult to form a dense film. Therefore, as the ALD film for filling the pinholes formed in the protective film of the organic EL element, an insulating film containing Al is preferred.

However, since the insulating film containing Al contains aluminum (Al), if it is in contact with moisture, it easily reacts with the moisture to form a reaction product and cause the insulating film containing Al to deteriorate. If the insulating film containing Al itself deteriorates, the effect of preventing the transmission of moisture through the pinholes is reduced by filling the pinholes with the insulating film containing Al.

Therefore, in the case of a protective film for an organic EL element, when a single-layer inorganic insulating film containing Si is formed using a plasma CVD method, pinholes formed in the inorganic insulating film containing Si become a problem, and the protection is caused. The film prevents deterioration of the moisture transmission function. On the other hand, in the case of a protective film for an organic EL element, when an inorganic insulating film containing Si is formed using a plasma CVD method, and a laminated film composed of an insulating film containing Al is formed thereon using an ALD method, the It is a problem that the insulating film containing Al easily reacts with moisture, and the moisture transmission prevention function of the protective film is reduced. Reliability of this system with organic EL elements This is related to a decrease in reliability of a display device (organic EL display device) using an organic EL element. Therefore, it is desired to improve the performance of the protective film for an organic EL element.

<About main features and effects>

One of the main features of this embodiment is that the protective film 16 of the organic EL element is an insulating film 16a formed using a plasma CVD method, an insulating film 16b formed using an ALD method, and an insulating film 16c formed using a plasma CVD method. Laminated film.

The insulating film 16a is formed using a plasma CVD method. In terms of the advantages of the plasma CVD method, for example, it is easy to control the stress of the film to be formed, and the coverage of the film to the bottom of the film (here, the organic EL element) is good. As for the insulating film 16a, it is preferable to use an inorganic insulating film containing Si formed by a plasma CVD method. Therefore, since the film can be formed at a low temperature and the film density is high, the film-forming process of the insulating film 16a is not affected. It has a bad effect on the organic EL element and can improve the function of preventing moisture from being transmitted to the insulating film 16a. As for the insulating film 16a, although a silicon nitride film, a silicon oxide film, or a silicon oxynitride film is preferably used, a silicon nitride film is most preferable. This is because, in the case of using a plasma CVD method, a denser silicon nitride film can be formed at a low temperature.

However, as a side effect of forming the insulating film 16a using the plasma CVD method, when the insulating film 16a is formed, a pinhole may be generated in the insulating film 16a. FIG. 17 is an enlarged cross-sectional view showing a part of the insulating film 16a in FIG. 9 (the step of forming the insulating film 16a at step S6a), and schematically shows the case where the insulating film 16a is formed by the plasma CVD method. The pinhole PH is formed in the insulating film 16a. If a pinhole PH is formed in the insulating film 16a, there is a possibility that moisture may enter the organic EL element through the pinhole PH.

Therefore, in this embodiment, the insulating film 16b is formed on the insulating film 16a. The insulating film 16b is an insulating film (inorganic insulating film) containing aluminum (Al) as a constituent element, that is, an insulating film containing Al (an inorganic insulating film containing Al), and more specifically, for example, an aluminum oxide film, aluminum nitride oxide Film or aluminum nitride film. Among these, the insulating film 16b is preferably an aluminum oxide film or an aluminum nitride oxide film. The insulating film 16b is preferably made of It is formed by the ALD method and can fill the pinholes of the insulating film 16a. When the ALD method is used as the film formation method, the above-mentioned Al-containing insulating film can form a dense film at a low temperature. Therefore, by using an Al-containing insulating film formed by the ALD method as the insulating film 16b, the film-forming process of the insulating film 16b does not adversely affect the organic EL element, and the insulating film 16b can be completely filled in the insulating film. The pinhole of the membrane 16a. FIG. 18 is an enlarged sectional view showing a part of the insulating films 16 a and 16 b in FIG. 10 (the step of forming the insulating film 16 b in step S6 b), and the insulating film 16 b is formed by using the ALD method, and is schematically shown. The pinhole PH of the insulating film 16a is filled with the insulating film 16b. By filling the pinhole formed in the insulating film 16a with the insulating film 16b, it is possible to prevent moisture from entering the organic EL element through the pinhole PH.

Next, in this embodiment, an insulating film 16c is formed on the insulating film 16b. The insulating film 16c is formed using a plasma CVD method. As for the insulating film 16c, it is preferable to use an inorganic insulating film containing Si formed by a plasma CVD method. Therefore, since the film can be formed at a low temperature and the film density is high, the film forming process of the insulating film 16c is not affected. It has a bad effect on the organic EL element and can enhance the function of the insulating film 16c to prevent moisture. As for the insulating film 16c, although a silicon nitride film, a silicon oxide film, or a silicon oxynitride film is preferably used, a silicon nitride film is most preferable. When the plasma CVD method is used to form a film, a denser silicon nitride film can be formed at a low temperature. FIG. 19 is an enlarged sectional view showing a part of the insulating films 16a, 16b, and 16c enlarged in FIG. 11 (the step of forming the insulating film 16c at step S6c), which schematically shows that the insulating film 16c is formed on the top surface of the insulating film 16b. status.

Since the insulating film 16c having a moisture barrier property is formed on the insulating film 16b, the insulating film 16b of the insulating film containing Al can be prevented from contacting with and reacting with moisture. That is, by forming an insulating film 16b of an insulating film containing Al on the insulating film 16a formed using a plasma CVD method, the pinhole formed in the insulating film 16a can be filled with the insulating film 16b, and Since the insulating film 16c is formed on the insulating film 16b, it is possible to prevent the insulating film 16b having the Al-containing insulating film easily reacting with moisture from reacting with moisture.

At the same time, because the insulating film 16c is formed by the plasma CVD method, although there is a possibility that pinholes are formed in the insulating film 16c, portions other than the pinholes have moisture barrier properties, so that the transmission of moisture can be prevented. At the same time, the area of the pinhole formed in the insulating film 16c is small compared to the entire insulating film 16c. Therefore, by forming the insulating film 16c on the insulating film 16b, it is possible to prevent moisture from being transmitted to the insulating film 16b through places other than the pinholes of the insulating film 16c, and by forming the insulating film 16c on the insulating film 16b, it can be prevented The insulating film 16b including an Al insulating film has an effect of contacting with and reacting with moisture.

Different from this embodiment, FIG. 20 is a cross-sectional view of a comparative example. The above comparative example is a case where a display device is manufactured without forming an insulating film 16c on the insulating film 16b (corresponding to the description in the above “process for discussion”). (Case), a state where the insulating film 16b reacts with moisture and deteriorates is schematically shown. If the insulating film 16c is not formed on the insulating film 16b, as shown in FIG. 20, there is a possibility that the insulating film 16b may react with moisture and deteriorate. On the other hand, in this embodiment, as shown in FIG. 19, by forming an insulating film 16c having a moisture barrier property on the insulating film 16b, it is possible to prevent the insulating film 16b from reacting with moisture and prevent it from being caused by the reaction with moisture. The deterioration of the insulating film 16b. Meanwhile, compared with the insulating film 16b, since the insulating film 16c is made of a material that is difficult to react with moisture, there is no doubt that the insulating film 16c reacts with moisture and causes deterioration.

In this way, in this embodiment, the protective film 16 is formed by transmitting the laminated film of the insulating film 16a, the insulating film 16b, and the insulating film 16c, the insulating film 16a and the insulating film 16c have moisture barrier properties, and the insulating film 16b The pinholes of the insulating film 16a can be filled, and the insulating film 16b can be prevented from contacting and reacting with moisture by the insulating film 16c. Thereby, the function of the protective film 16 to prevent (shield) the transmission of moisture can be enhanced, and the effect of preventing the transmission of moisture to the organic EL element can be enhanced by the protective film 16. Therefore, the performance of the protective film 16 for an organic EL element can be improved. because Accordingly, the reliability of the organic EL element can be improved, and the reliability of a display device (organic EL display device) using the organic EL element can be improved.

Although the protective film 16 of this embodiment has a three-layer structure of an insulating film 16a, an insulating film 16b, and an insulating film 16c, this corresponds to a film (thickness portion) of a Si-containing inorganic insulating film formed by a plasma CVD method. A structure containing an Al insulating film is inserted.

As explained in the above "About the Process of Investigation", although the Si-containing inorganic insulating film formed using the plasma CVD method has moisture barrier properties and is used as a protective film, it is easy to form pinholes, and moisture can pass through. Pinholes convey doubts. In contrast, in the case where a two-layer protective film is formed on the top surface of an inorganic insulating film containing Si formed by a plasma CVD method and an insulating film containing Al formed by an ALD method is used, an insulating film containing Al is provided. Doubts about membranes reacting with moisture. On the other hand, an Si-containing inorganic insulating film formed by the ALD method is provided under the Si-containing inorganic insulating film formed by the plasma CVD method. When two protective films are formed, the Si-containing inorganic insulating film cannot be filled. There are pinholes in the membrane, and there is a doubt that moisture will pass through the pinholes.

In contrast, the structure of the protective film 16 according to the present embodiment corresponds to a structure in which an Al-containing insulating film is inserted into a film (thickness portion) containing a Si-containing inorganic insulating film formed by a plasma CVD method. In other words, the Si-containing inorganic insulating film (16a, 16c) formed using the plasma CVD method has a structure in which an insulating film (16b) containing Al formed using the ALD method is sandwiched. Thereby, the pinholes in the lower layer of the Si-containing inorganic insulating film can be filled with the insulating film (16b) containing Al, and at the same time, the insulating film (16b) containing Al can be suppressed or prevented from reacting with moisture.

Further features of this embodiment will be described.

In this embodiment, while the insulating film 16a, the insulating film 16b, and the insulating film 16c are used as the protective film 16, the thicknesses of the insulating film 16a, the insulating film 16b, and the insulating film 16c are also adjusted. Specifically, it is as follows.

Since an inorganic insulating film is less likely to pass moisture than an organic insulating film, it is suitable as a protective film for an organic EL element. Therefore, each of the insulating films 16a, 16b, and 16c constituting the protective film 16 uses an inorganic insulating film. However, since the inorganic insulating film is harder than the organic insulating film, if it is too thick, cracks are likely to occur. Therefore, it is desirable to reduce the thickness of the protective film 16 so that the protective film 16 is less prone to cracks. In particular, compared with a case where a hard substrate such as a glass substrate is used, when a flexible substrate having flexibility is used as the substrate 11, the protective film is easily cracked due to the stress when the substrate 11 is bent. Therefore, especially when a flexible flexible substrate is used as the substrate 11, it is important to reduce the thickness of the protective film 16 in order to prevent the protective film 16 from easily cracking.

Therefore, although it is desirable to suppress the thickness of the protective film 16 in this embodiment, even if the thickness of the protective film 16 is suppressed, it is necessary to ensure the effect of the protective film 16 against the intrusion of moisture.

Therefore, in this embodiment, while the protective film 16 is formed by a laminated film of the insulating films 16a, 16b, and 16c, the thickness (film thickness) T1 of the insulating film 16a is larger than the thickness (film thickness) of the insulating film 16b. And the thickness (film thickness) of the insulating film 16c (that is, T1> T2 and T1> T3). Accordingly, even if the thickness of the protective film 16 is suppressed, the effect of preventing the intrusion of moisture into the protective film 16 can be efficiently ensured. The reason will be described below.

In other words, since the moisture barrier property of the inorganic insulating film containing Si is higher than that of the insulating film containing Al, the water permeability per unit thickness is low. Therefore, the moisture transmission rate per unit thickness of the insulating films 16a and 16c becomes lower than that of the insulating film 16b. At the same time, if the insulating film edge 16a is compared with the insulating film edge 16c, the pinholes relative to the insulating film edge 16a are filled with the insulating film 16b, because the pinholes of the insulating film edge 16c are not filled with the insulating film 16b, so the needle The moisture permeability per unit thickness of the insulating film edge 16a whose holes are filled with the insulating film 16b becomes lower than that of the insulating film 16c where the pinholes are not filled. In other words, because the pinholes of the insulating film 16a are filled with the insulating film 16b, the function of the moisture transmission path cannot be exerted. On the other hand, because the pinholes of the insulating film 16c are not filled with the insulating film 16b, the moisture can be exerted. Since the function of the via is transmitted, the water permeability per unit thickness of the insulating film 16a becomes lower than that of the insulating film 16c. because Therefore, among the insulating films 16a, 16b, and 16c, the insulating film 16a has the lowest moisture permeability per unit thickness.

Therefore, in the present embodiment, among the thicknesses of the protective film 16, the thickness assigned to the insulating film 16a is larger than the thickness assigned to each of the insulating film 16b and the insulating film 16c. That is, the thickness T1 of the insulating film 16a is thicker than the thickness T2 of the insulating film 16b, and is thicker than the thickness T3 of the insulating film 16c (that is, T1> T2 and T1> T3). Among the insulating films 16a, 16b, and 16c, by making the thickness of the insulating film 16a having the lowest moisture transmission rate per unit thickness the thickest, the effect of preventing the intrusion of moisture into the protective film 16 can be improved; The thickness of each of the insulating films 16b and 16c, which has a higher moisture permeability per unit thickness than the insulating film 16a, is reduced, and the thickness of the entire protective film 16 can be suppressed. Thereby, while the thickness of the protective film 16 can be suppressed, the effect of preventing the intrusion of moisture into the protective film 16 can be obtained efficiently.

That is, it is assumed that the thickness of the protective film 16 is a specific value. In this case, if the thickness of the insulating films 16b and 16c is made thick, and only the thickness of the insulating film 16a is made thin, when the thickness of the insulating film 16a having the lowest moisture permeability per unit thickness becomes thin, the protective film 16 becomes thin. The overall moisture transmission rate becomes higher. On the other hand, if the thicknesses of the insulating films 16b and 16c are made thin, and only the thickness of the insulating film 16a is made thick, when the thickness of the insulating film 16a having the lowest moisture permeability per unit thickness becomes thick, the protective film 16 is made thick. The overall moisture transmission rate is reduced. Therefore, in order to effectively increase the effect of the protective film 16 against moisture intrusion without increasing the overall thickness of the protective film 16, the thickness of the insulating films 16b and 16c is reduced, and only the thickness of the insulating film 16a is reduced. Thick is effective. Therefore, among the thicknesses of the protective film 16, the thickness assigned to the insulating film 16a is larger than the thickness assigned to the insulating films 16b and 16c, respectively, and the thicknesses T1, T2, and T2 of the insulating films 16a, 16b, and 16c, respectively. T3 satisfies the relationship of T1> T2 and T1> T3. It is preferable if the relational expression of T1> T2 + T3 (the relational expression of the thickness T1 of the insulating film 16a larger than the sum of the thicknesses T2 and T3 of the insulating films 16b and 16c) is satisfied.

Meanwhile, in the thickness of the protective film 16, although the thickness allocated to the insulating film 16b is smaller than the thickness allocated to the insulating film 16a (that is, the thickness T2 of the insulating film 16b is thinner than the thickness T1 of the insulating film 16a), If the thickness of the film 16b is too thin, there is a concern that the insulating film 16b cannot be used to sufficiently fill the pinholes formed in the insulating film 16a. Therefore, the thickness T2 of the insulating film 16b formed in step S6b is preferably 10 nm or more (T2 ≧ 10 nm), and more preferably 15 nm or more (T2 ≧ 15 nm). Thereby, even if the insulating film 16a is formed with a pinhole when the insulating film 16a is formed by the plasma CVD method in step S6a, the insulating film 16b can be reliably used when the insulating film 16b is formed by the ALD method in step S6b. The pinholes are filled. Accordingly, the effect of preventing the intrusion of moisture into the protective film 16 can be obtained more reliably.

At the same time, since the water permeability per unit thickness of the insulating film 16b is higher than that of the insulating films 16a and 16c, from the viewpoint of the overall thickness of the protective film 16, as long as the thickness T2 of the insulating film 16b can be ensured, It is sufficient to fill the thickness of the pinhole of the insulating film 16a, and it is advantageous not to be too thick. At the same time, because the film formation speed of the ALD method is slow, from the viewpoint of reducing the manufacturing time and increasing the throughput, as long as the thickness T2 of the insulating film 16b can be ensured to fully fill the thickness of the pinhole of the insulating film 16a, It is more advantageous not to be too thick. Under these viewpoints, the thickness T2 of the insulating film 16b formed in step S6b is preferably 50 nm or less (T2 ≦ 50 nm). Therefore, the thickness T2 of the insulating film 16b is preferably 10 to 50 nm, and more preferably 15 to 50 nm.

At the same time, although the moisture transmission rate per unit thickness of the insulating film 16a is lower than that of the insulating film 16c, the insulating film 16a is thicker than the insulating film 16c. Therefore, the effect of the protective film 16 against moisture intrusion can be improved. If the thickness T3 is too thin, the effect of the insulating film 16c on preventing the insulating film 16b from reacting with moisture may be reduced. Therefore, the thickness T3 of the insulating film 16c formed in step S6c is preferably 10 nm or more (T3 ≧ 10 nm), and more preferably 15 nm or more (T3 ≧ 15 nm). Thereby, the insulating film 16c can reliably prevent the insulating film 16b from reacting with moisture.

FIG. 21 is a cross-sectional view schematically showing that the flexible substrate is bent when the flexible substrate is used as the substrate 11 of the display device 1. Although FIG. 21 is a cross-sectional view, the hatching is omitted for easy viewing. If a flexible substrate is used as the substrate 11 of the display device 1, the display device 1 is flexible.

In the case where a flexible substrate is used as the substrate 11, since the tortuosity is accompanied by a risk of cracks in a protective film made of an inorganic insulating film, it is desirable that the protective film made of an inorganic insulating film be as thin as possible. Therefore, in the case where a flexible substrate is used as the substrate 11, the effect of achieving the effect of preventing the invasion of moisture of the protective film 16 while suppressing the thickness of the protective film 16 is very effective. big.

Meanwhile, in the case where a flexible substrate is used as the substrate 11, even when the flexible substrate (display device) is tortuous with a small meandering radius, it is effective to reduce the thickness of the protective film 16 so as not to cause cracks in the protective film 16. In addition, if the thickness of the protective film 16 is less than 20 nm, it is particularly suitable. However, thinning the thickness of the protective film 16 has a concern of increasing the risk of water intrusion. In contrast, in this embodiment, by performing the above adjustment, the thickness of the protective film 16 can be suppressed, and the effect of preventing the intrusion of moisture into the protective film 16 can be obtained efficiently. Even when the thickness is 200 nm or less, the effect of preventing the intrusion of moisture by the protective film 16 can be reliably obtained. Therefore, if this embodiment is applied, the thickness of the protective film can be reduced while reliably obtaining the effect of preventing the intrusion of moisture by the protective film 16, for example, the thickness becomes 200 nm or less. When the flexible substrate (display device) is meandered, cracks in the protective film 16 can be prevented. The thickness of the protective film 16 is 200 nm, which corresponds to the total value of the thickness T1 of the insulating film 16a, the thickness T2 of the insulating film 16b, and the thickness T3 of the insulating film 16c. The total value is 200 nm or less (ie, T1 + T2 + T3 ≦ 200 nm).

At the same time, in order to enhance the effect of preventing the intrusion of moisture into the protective film 16, it is effective to increase the density of the insulating films 16a and 16c (especially the insulating film 16a). Increasing the density of the insulating films 16a and 16c can improve the moisture barrier properties of the insulating films 16a and 16c except for the pinholes. Therefore, when the insulating film 16a is formed by the plasma CVD method in step S6a, it is preferable to use the ICP-CVD method. Meanwhile, in step In the case where the insulating film 16c is formed by the plasma CVD method in S6c, the ICP-CVD method is preferably used. Compared with CCP (Conductively Coupled Plasma) -CVD (Inductively Coupled Plasma CVD) method, etc., ICP-CVD method can easily achieve higher plasma density (plasma electron density), and can suppress the film formation temperature and Easily increase the density of the formed film. By using the ICP-CVD method in the formation process of the insulating films 16a and 16c, the density of the insulating films 16a and 16c can be increased while suppressing the film forming temperature, and the effect of preventing the intrusion of moisture by the protective film 16 can be further enhanced. . Therefore, the thickness of the protective film 16 can be suppressed, and the effect of preventing the intrusion of moisture into the protective film 16 can be further enhanced.

Meanwhile, although the inorganic insulating film is a film that is difficult for moisture to pass through, it is also a hard film. Therefore, the resin film 17 can be formed on the protective film 16, that is, on the insulating film 16 c. The resin film 17 can be used as the uppermost film of the display device 1. Compared with the inorganic insulating film (16), since the resin film (17) allows water to pass easily, the resin film (17) is not effective as a film for preventing water from entering. However, the resin film (17) is softer than the inorganic insulating film (16). Therefore, by forming the soft resin film 17 on the protective film 16, it becomes possible to easily handle the display device 1. At the same time, the resin film 17 can function as a protective film (mechanical protective film) resistant to physical impact. At the same time, when a flexible substrate is used as the substrate 11, by forming the resin film 17 on the protective film 16, it is possible to more reliably prevent the protective film 16 from being broken along with the twist.

Meanwhile, when the resin film 17 is formed on the protective film 16, the protective film 16 and the resin film 17 are considered together as a protective film. That is, when the resin film 17 is formed, a laminated film formed of the insulating film 16a, the insulating film 16b, the insulating film 16c, and the resin film 17 can be regarded as a protective film. However, in the case where the resin film 17 is formed, a film having a function of preventing moisture from entering (a moisture prevention film) refers to a laminated body (laminated) of an insulating film 16a, an insulating film 16b, and an insulating film 16c. Film), and the resin film 17 mainly functions as a mechanical protective film. The moisture protection film (herein, the protection film 16) is made of an inorganic insulator, and the mechanical protection film (herein, the resin film 17) is made of a resin material (organic insulator).

Meanwhile, unlike the present embodiment, it is assumed that the resin film 17 is formed directly on the insulating film 16b instead of forming the insulating film 16c. In this case, because the resin film easily allows moisture to pass through, even if the resin film 17 is formed on the insulating film 16b, the moisture that passes through the resin film 17 reaches the insulating film 16b, and this moisture is formed by the insulating film containing Al. The insulating film 16b reacts to cause deterioration of the insulating film 16b.

On the other hand, in this embodiment, the film formed on the insulating film 16b in contact with the insulating film 16b is not a resin film, but an insulating film 16c made of an inorganic insulating film containing Si. This insulating film 16c is less likely to pass moisture than a resin film. By forming the insulating film 16c directly on the insulating film 16b, it is possible to reliably prevent the insulating film 16b made of an insulating film containing Al from reacting with moisture.

FIG. 22 is a graph showing the experimental results obtained with respect to the water permeability of the protective film. FIG. 22 shows the results of measuring the WVTR (Water Vapor Transmission Rate) using the Ca method (calcium method) for samples A, B, and C.

Sample A corresponds to the case where a single-layer silicon nitride film is formed by a plasma CVD method. Sample B corresponds to the case where a two-layer protective film of an aluminum oxide film is formed on a single-layer silicon nitride film formed by a plasma CVD method and then an ALD method is used. Sample C corresponds to the third of a single-layer silicon nitride film formed by plasma CVD method, and then an aluminum oxide film formed by ALD method, and a silicon nitride film is formed by plasma CVD method on the alumina film. In the case of a protective film. In each of sample A, sample B, and sample C, a protective film was formed on the substrate, and the WVTR of the protective film was measured using the Ca method. At the same time, the thicknesses of the protective films in samples A, B and C are the same. In addition, sample A and sample B correspond to the protective film described in the above-mentioned "Proceeding" column, and sample C corresponds to the protective film 16 of this embodiment.

22, with respect to WVTR sample A, sample B (unit: g‧m ^-2 ‧day ^-1) based 1.7x10 ^-3, 3x10 ^-4, C WVTR of the sample under the detection limit, i.e., 1x10 ^{- 6} or less. From this result, it is understood that the water permeability of Sample C is very small compared to Sample A and Sample B. This is because, compared with the protective films of samples A and B, the protective film corresponding to sample C of the protective film 16 of this embodiment makes it difficult for water to pass through, and it shows that it is a very excellent film that prevents water from entering. In this embodiment, as described above, by using the laminated film of the insulating film 16a, the insulating film 16b on the insulating film 16a, and the insulating film 16c on the insulating film 16b as the moisture prevention film, it is possible to reliably prevent moisture. Communicate to organic EL elements.

As mentioned above, although the invention completed by the present inventors has been specifically described based on the embodiments of the present invention, the present invention is not limited to the foregoing embodiments, and can be made in various ways as long as it does not depart from the scope of the concept of the present invention. The change.

Claims (20)

A method for forming a protective film for an organic EL element, comprising the following steps: (a) forming a first insulating film containing Si using a plasma CVD method to cover the organic EL element formed on a flexible substrate; (b) ) Forming a second insulating film containing Al on the first insulating film using ALD method; (c) forming a third insulating film containing Si on the second insulating film using plasma CVD method; An insulation film, a second insulation film, and a third insulation film to form a protective film for the organic EL element; and a first thickness of the first insulation film is larger than that of the second insulation film The second thickness is also thick, and the first thickness of the first insulating film is also thicker than the third thickness of the third insulating film. The method for forming a protective film for an organic EL element according to claim 1, wherein the first insulating film is made of a silicon nitride film, a silicon oxide film, or a silicon oxynitride film, and the second insulating film is made of The third insulating film is made of a silicon nitride film, a silicon oxide film, or a silicon oxynitride film. The method for forming a protective film for an organic EL element according to claim 1, wherein the first insulating film is made of a silicon nitride film, and the second insulating film is made of an aluminum oxide film or an aluminum nitride oxide film. The third insulating film is made of a silicon nitride film. The method for forming a protective film for an organic EL element according to claim 1, wherein the second thickness of the second insulating film is 10 nm or more. The method for forming a protective film for an organic EL element according to claim 4, wherein the third thickness of the third insulating film is 10 nm or more. The method for forming a protective film for an organic EL element according to claim 1, wherein the plasma CVD method described in steps (a) and (c) is an ICP-CVD method. The method for forming a protective film for an organic EL element according to claim 1, wherein the second insulating film is connected to the first insulating film, and the third insulating film is connected to the second insulating film. The method for forming a protective film for an organic EL element according to claim 1, wherein the total of the first thickness, the second thickness, and the third thickness is 200 nm or less. A method for manufacturing a display device includes an organic EL element and includes the following steps: (a) forming the organic EL element on a flexible substrate; (b) forming a first insulating film containing Si using a plasma CVD method to cover (C) forming a second insulating film containing Al on the first insulating film using the ALD method; (d) forming a third insulating film containing Si on the second insulating film using the plasma CVD method A film; wherein a protective film for an organic EL element is formed by a laminated film formed of the first insulating film, the second insulating film, and the third insulating film; and a first thickness of the first insulating film It is thicker than the second thickness of the second insulating film, and the first thickness of the first insulating film is also thicker than the third thickness of the third insulating film. The method for manufacturing a display device according to claim 9, wherein the first insulating film is made of a silicon nitride film, a silicon oxide film, or a silicon oxynitride film, and the second insulating film is made of an aluminum oxide film, The third insulating film is made of a silicon nitride film, a silicon oxide film, or a silicon oxynitride film. The method for manufacturing a display device according to claim 9, wherein the first insulating film is made of a silicon nitride film, and the second insulating film is made of an aluminum oxide film or an aluminum nitride oxide film, and the The third insulating film is made of a silicon nitride film. The method for manufacturing a display device according to claim 9, further comprising: (e) forming a resin film on the third insulating film after step (d). The method for manufacturing a display device according to claim 9, wherein the second thickness of the second insulating film is 10 nm or more. The method for manufacturing a display device according to claim 13, wherein a third thickness of the third insulating film is 10 nm or more. The method for manufacturing a display device according to claim 9, wherein the total of the first thickness, the second thickness, and the third thickness is 200 nm or less. The method for manufacturing a display device according to claim 9, wherein the plasma CVD method described in steps (b) and (d) is an ICP-CVD method. The method for manufacturing a display device according to claim 9, wherein the second insulating film is connected to the first insulating film, and the third insulating film is connected to the second insulating film. A display device includes: a flexible substrate; an organic EL element formed on the flexible substrate; a first insulating film containing Si is formed to cover the organic EL element; and a second insulating film is formed on the first On the insulating film; a third insulating film is formed on the second insulating film; wherein the first insulating film is formed by a plasma CVD method, and the first insulating film is made of a silicon nitride film, a silicon oxide film, or nitrogen The second insulating film is formed using an ALD method, and the second insulating film is formed of an aluminum oxide film, an aluminum nitride film, or an aluminum oxynitride film; and the third insulating film is formed using a plasma CVD method. And the third insulating film is made of a silicon nitride film, a silicon oxide film or a silicon oxynitride film; and a laminated film made of the first insulating film, the second insulating film, and the third insulating film. To form the protective film for the organic EL element; and the first thickness of the first insulating film is thicker than the second thickness of the second insulating film, and the first thickness of the first insulating film is also larger than the third thickness The third thickness of the insulating film is also thick. The display device according to claim 18, wherein a resin film is further formed on the third insulating film. The display device according to claim 18, wherein a total of the first thickness, the second thickness, and the third thickness is 200 nm or less.